Misdiagnosed otitis media (OM) is a leading cause of overmedication with antibiotics in children. The alarming consequence of unnecessary antibiotic use is increasing resistance to antibiotics among bacterial strains responsible for OM. The accuracy of currently available noninvasive detection methods of middle ear effusion is not satisfactory, especially when the test is performed by primary health care providers. In Phase I we demonstrated the feasibility of noninvasive detection of middle ear effusion based on the analysis of ultrasonic echoes reflected from the tympanic membrane and the middle ear cavity. We achieved a statistically significant (P = 0.004) correlation between our ultrasonic method and myringotomy in the detection of the effusion and in differentiation between serous and mucoid states of the fluid. In Phase II, we propose development of a refined ultrasonic probe and analysis software to allow noninvasive detection of middle ear effusion and the estimation of the viscosity of the fluid occupying the middle ear. This latter feature is not available with any existing noninvasive detection method. We will develop a miniature ultrasonic curved array transducer, which will be incorporated into an earplug (probe). The probe will allow for fast acquisition of ultrasonic scans from the ear canal and middle ear cavity. Designated software, which will be developed in this project, will extract diagnostically significant features of the scan and it will display the result in easy for interpretation format. The device we propose will allow diagnostic testing on conscious pediatric patients in the average medical office setting and will provide information for accurate diagnosis of middle ear effusion.